1. Field of the Invention
The present invention relates to a drying system of a coated continuous film and in particular a system equipped with roller conveyor devices of said continuous film.
In detail, the invention relates to a drying system of a coated continuous film equipped with roller conveyor devices of the continuous film that allow easy and rapid removal of the rollers from the system to facilitate cleaning and maintenance operations.
2. Description of the Related Art
Said drying systems are substantially constituted by a tunnel through which a continuous film coated with a coating, such as adhesive or the like, is fed to heat said coating and allow evaporation of any solvents and humidity contained therein.
Most of these systems are provided internally with a plurality of motorized conveyor rollers adapted to convey said continuous film from an inlet side toward an outlet side, as well as to support said film inside the tunnel.
In prior art systems, said conveyor rollers comprise a cylinder to guide and support the continuous film, if necessary coated with a material with high friction coefficient, supported at the ends by two shafts integral with said cylinder and housed on support means housed in the frame of the system.
In detail, one of said support shafts of the roller conveyor device is also connected to motion transmission means, such as pulleys, sprockets or the like, which transmit motion from motor means to said conveyor roller.
To heat the coating material of the continuous film, for example adhesive or the like, jets or hot air are generally used, directed on the coated side of the film to cause evaporation and subsequent dispersion and expulsion of any solvents or humidity contained in said coating material.
During the air blowing operation, a non-volatile fraction of the coating material of the film may be nebulised by the jets of air and subsequently deposited on the whole of the inner surface of the tunnel and on the various components present inside the tunnel, in particular on the guide cylinders of the conveyor rollers.
Besides soiling the film during conveying thereof, the presence of this deposit of material on the rollers often causes noteworthy problems of alignment of the film inside the machine, above all when the section of continuous film being conveyed inside the tunnel reaches significant lengths (up to ten meters).
To prevent the aforesaid problems, these systems therefore require periodic internal cleaning, in particular thorough cleaning of the conveyor rollers. Currently, said cleaning operations can be carried out using two different methods, both somewhat inconvenient.
With the first method, the rollers are disassembled and cleaning is performed outside the machine.
This solution, which would undoubtedly ensure a satisfactory result from the point of view of cleaning, would however involve a substantial loss of time and unacceptable machine downtime and therefore is almost never used.
In fact, to remove the rollers from the machine it is necessary to dismantle the two roller supports and remove all the motion transmission elements that are connected to one of the two support shafts of said roller.
With the second method, cleaning is performed directly inside the machine without removing the rollers.
Therefore, in this case it is not necessary to disassemble the machine but, due to the small handling spaces inside the machine, the operator performing the operation is obliged to carry out a series of complicated manoeuvres that make it impossible for cleaning to be as accurate as when it is performed outside the machine.
Moreover, these components of the system are usually at a temperature that can even reach 150° C.; consequently the operator must wait several minutes before being able to perform the cleaning operations inside the machine.
In any case, when it is essential to disassemble the rollers, for example to carry out extraordinary maintenance, the time required for their removal from the system considerably affects the total time of the operation and therefore the machine downtime.